1. Field of the Invention
The present invention relates to a recording apparatus for recording an image on a recording medium supplied one by one.
2. Related Background Art
FIG. 10 shows a conventional color recording apparatus of an ink jet recording type. The recording apparatus serves to record a color image on a small size recording medium such as a visiting card or a post card.
The recording apparatus includes a sheet supply portion 200 for supplying recording media S one by one to a main body 100 of the recording apparatus, a recording convey portion 300 for conveying the recording medium S supplied from the sheet supply portion 200 at a predetermined speed in a horizontal direction, an image recording portion 400 for recording an image on the recording medium S being conveyed by the recording convey portion 300, and a discharge stacking portion 500 for discharging and stacking the recording media S on which the images were recorded in the image recording portion 400.
The sheet supply portion 200 comprises a sheet supply tray 201, a pick-up roller 202, a separation pad 203, a pair of separation supply rollers 204, 205, and a shutter 206. The pick-up roller 202 is rotated in a clockwise direction to feed out the uppermost recording media S from those stacked on the sheet supply tray 201. The sheet supply tray 201 is lifted by a predetermined amount whenever a predetermined number of recording media S are fed out, so that the uppermost recording medium S is contacted with the pick-up roller 202 with predetermined pressure.
The recording media S fed out by the pick-up roller 202 are pre-separated by the inclined separation pad 203 and then are separated and supplied one by one by the pair of separation supply rollers 204, 205.
The supply roller 205 is rotated in a clockwise direction. The separation roller 204 is normally rotated in an anti-clockwise direction. However, if a plurality of recording media S are supplied in a nip between the supply roller 205 and the separation roller 204, the separation roller is rotated in a clockwise direction by the action of a torque limiter (not shown). Skew-feed of the recording medium S fed by the pair of separation supply rollers 204, 205 is corrected by abutting the recording medium against the shutter a tip end of which blocks a sheet path. After the skew-feed of the recording medium is corrected, the shutter 206 is retarded from the sheet path.
The recording convey portion 300 includes an endless convey belt 301, a driven roller 302 cooperating with the convey belt 301 to pinch the recording medium S therebetween at a most upstream end of the convey belt, and a plurality of spur wheels 303 to 307 for holding down the recording medium S on the convey belt 301 at a downstream area of the driven roller 302. The convey belt 301 is mounted and wound around a drive roller 308 rotated in an anti-clockwise direction and a driven roller 308 and extends in a horizontal direction. The driven roller 302 is opposed to the drive roller 308 and is biased toward the drive roller 308 by a biasing means (not shown) such as a spring so that the driven roller 302 is contacted with the convey belt 301 with predetermined pressure.
The leading end of the recording sheet S the skew-feed of which was corrected by the shutter 206 enters into a nip between the convey belt 301 rotated in the anti-clockwise direction and the driven roller 302 rotatingly driven by the rotation of the convey belt 301. The recording medium S is conveyed onto the convey belt 301 while being pinched between the convey belt 301 and the driven roller 302. The recording medium S on the convey belt 301 rotated in the anti-clockwise direction is conveyed toward a downstream side while being held down by the spur wheels 303 to 307 rotatingly driven by the rotation of the convey belt 301.
The image recording portion 400 includes a plurality of ink jet recording heads 400B, 400C, 400M and 400Y spaced apart from each other by a predetermined distance along a recording medium conveying direction. The recording head 400B serves to discharge black color ink, recording head 400C serves to discharge cyan color ink, recording head 400M serves to discharge magenta color ink and recording head 400Y serves to discharge yellow color ink.
When the recording medium S conveyed by the convey belt 301 reaches the recording head 400B, the recording head 400B discharges the black color ink, thereby recording a black color image. Then, when the recording medium S reaches the recording head 400C, the recording head 400C discharges the cyan color ink, thereby recording a cyan color image. Then, when the recording medium S reaches the recording head 400M, the recording head 400M discharges the magenta color ink, thereby recording a magenta color image. Then, when the recording medium S reaches the recording head 400Y, the recording head 400Y discharges the yellow color ink, thereby recording an yellow color image.
The discharge stacking portion 500 includes a sheet discharge tray 501, a first discharge roller 502, and a second discharge roller 503. The recording medium S on which the image was recorded is discharged out of the apparatus while being pinched between the first discharge roller 502 and a spurred roller 504. The recording medium S discharged out of the apparatus is discharged onto the sheet discharge tray 501 while being pinched between the second discharge roller 503 and a spurred roller 505.
However, in the above-mentioned conventional recording apparatus, since (1) the recording medium S is conveyed onto the convey belt 301 while being pinched between the convey belt 301 and the driven roller 302, and (2) the recording medium S is fed to the convey belt 301 by the pair of separation supply rollers 204, 205 pinching the recording medium S, the following problems arose.
That is to say, firstly, as shown in FIG. 11, when the recording medium S-1 supplied by the pair of separation supply rollers 204, 205 strides over between the pair of separation supply rollers 204, 205 and the convey belt 301, the rotations of the pair of separation supply rollers 204, 205 influence upon the rotation of the convey belt 301 through the recording medium S-1. Thus, it is very difficult to stably convey the recording medium S-2 being conveyed by the convey belt 301 and being recorded, at the predetermined speed, thereby reducing the recording quality.
Secondly, as shown in FIG. 12, the recording medium S-2 being conveyed by the convey belt 301 and being recorded is subjected to conveyance resistance at a time when a trail end of the recording medium leaves the nip between the convey belt 301 and the driven roller 302, thereby worsening the recording quality.
The above first and second problems are noticeable particularly when the recording medium S is a thick sheet having a thickness of 200 microns or more.